The major goal of this study is to determine the relationship of the Restless Legs Syndrome (RLS) to potential risk factors: ethnicity and both physical and mental health. Another goal is to explore the relationship of RLS to sleep and function/disability. The analysis will use the database accumulated since 1980 in the East Baltimore Cachment area study (EGA). Questions on diagnostic features of RLS are included within the current wave of EGA. Accumulated data includes information on the subjects' demographics, social and functional situation, physical and psychological health. About 1/3 of the subjects are African-American. Specific Aims: 1) To determine whether RLS has a different prevalence in the African-American and Caucasian populations. There is a strong clinical suspicion that RLS is less prevalent in African-American populations, but evidence is lacking. If ethnic differences are found, they may be related to other characteristics of the two populations. 2) To determine whether longitudinal health measures or laboratory values provide robust risk measures for development of RLS. Previous studies have indicated that both poor physical and mental health are related to RLS. The wealth of longitudinal measures in the EGA database provide the opportunity to examine RLS in relationship to lifetime histories of physical and mental disorders. Laboratory values for APO-E types and iron measures included in the database can provide direct links to biological variables. 3) To determine whether RLS symptoms contribute to the burden of sleep problems and function /disability in individuals. Information on these issues in the EGA database will exploration on whether RLS makes a significant contribution to these major public health problems. The value of these data analyses will be enhanced by the independent, blinded confirmation of the RLS screening questions (in approximately 20% of all subjects) using a validated diagnostic interview.